Modern vehicles utilize fuel management systems that control fuel vapor venting from a vehicle fuel tank to limit fuel filling and that control fuel tank ventilation to prevent overpressure and vacuum conditions in the fuel tank. Fuel filling is controlled to allow a headspace of fuel vapor to exist above a fuel level in the fuel tank. This allows vapors to vent to a fuel vapor recovery device during thermal expansion, on-grade parking, and other similar conditions.
Exemplary embodiments of a fill limit vent valve (FLVV) may include a float device responsive to a buoyant force of fuel in the fuel tank. Thus when a fuel filled level is reached, the float may block an upper side of the FLVV and prevent fuel from entering the fuel tank. This enables the fuel tank to maintain a desired headspace of fuel vapor while signaling to a fuel pump operator that the fuel tank has reached a full condition. Furthermore, fuel vapor may not vent to a purge system of a fuel assembly when the float blocks the upper side of the FLVV.
Fuel levels in the fuel tank may decrease during vehicle operation and cause actuation of the float away from the upper side of the FLVV. The float may contact a lower side of the FLVV during fuel depletion and produce an undesired noise capable of penetrating a body of the fuel tank, audible to an operator or passengers of the vehicle.
Attempts to address noise permeation from actuation of the float in the FLVV include coupling a damping device to an interior portion of the FLVV. One example approach is shown by Ko et al. in U.S. Pat. No. 8,869,818. Therein, a valve body of the FLVV is prevented from hitting a lower body of the FLVV via a damping device located between the valve body and a lower end. The damping device includes elastic arms capable of absorbing the kinetic motion due to displacement of the valve body in response to buoyant forces.
However, the inventors herein have recognized potential issues with such systems. As one example, a profile of the FLVV is elongated to accommodate insertion of the damping device between the valve body and the lower end of the FLVV. Furthermore, the damping device may degrade, resulting in loose pieces of the damping device being located in an interior portion of the FLVV between the valve body and the lower body. This may cause the valve body to be fixed in a single position, which may prevent fuel from entering the fuel tank. As another example, the manufacturing and installation of the damping device may be difficult due to disassembling the FLVV in order to gain access to the damping device.
In one example, the issues described above may be addressed by a fluid tank comprising float axially displaceable in a valve, where the float sealingly engages an outlet of the valve in an upper position, and where the float contacts a lower portion of the valve in a lower position, and where a protuberance of the float extends through an opening of the lower portion and engages with a noise attenuation device outside an annular passage of the valve. In this way, a noise generated by the float contacting the base of the FLVV is decreased
As one example, the noise attenuation device is adjustable and may be easily added onto current FLVV's by manipulating a shape of the flexible wire to correspond with the FLVV shape. The noise attenuation device may absorb a portion of kinetic energy from the float as it moves to the lower position, and then return a portion of the portion of kinetic energy absorbed back to the float, thereby pushing it slightly toward an upper position. In this way, the noise attenuation device comprises a soft landing platform for the float while also providing a mechanism to aid in lifting the float.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.